        html,
        body {
            height: 100%;
            width: 100%;
            display: flex;
            justify-content: start;
            align-items: start;
            position: relative;
        }
        /* html {
            overflow-y: auto;
            overflow-x: hidden;
        }
        .box {
            margin-right: calc(100% - 100vw);
        } */
        .box {
            width: 100%;
        }
        .head {
            /* width: 1644px; */
            background-color: chocolate;
            display: flex;
            justify-content: space-between;
            /* position: relative; */
        }

        .head-left {
            display: flex;
        }
        .head > span {
            display: inline-block;
            text-align: center;
            margin-top: 5px;
        }
        a {
            display: inline-block;
            text-align: center;
            margin-top: 5px;
        }
        /* .head-a {
            margin-right: 775px;
        } */
        [class^="head_box"] {
            height: 20px;
            width:20px;
            margin: 4px;
            border: 1px solid #fff;
            border-radius: 10%;
        }
        button {
            margin: 4px;
            border: 0;
            border-radius: 5%;
            background: linear-gradient(#fff,#99ccff);
        }
        .sprict-line {
            height: 4px;
            background: #0000ff;
        }
        
        @media screen and (max-device-width: 882px) {  /*根据两端div来定*/
            /* body {
                background-color: yellow;
            } */
            .head {
                display: none;
                visibility: hidden;
            }
            .sprict-line {
                display: none;
                visibility: hidden;
            }
            .title_center {
                margin-top: -10%;
            }
        }   

        .center {
            width: 100%;
        }
        .box_center {
            margin-top: 3%;
            display: flex;
            justify-content: center;
            align-items: center;
            position: relative;
        }
        .box_button—center {
            margin-top: 3%;
            display: flex;
            justify-content: center;
            align-items: center;
            position: relative;
            /*position: relative;
            left: 50%;
             transform: (-50%,-50%); */
        }
        .title_center {
            top: 20%; 
            left: 10%;
            right: 10%;
            position: absolute;
            transform: (-50%,-50%);
        }
        .title_center > span{
            display: inline-block;
            margin-top: 15px;
            text-indent: 3em;   /*缩进度*/
            font-family: '宋体';
        }
        
        .hidden_box {
            width: 100%;
        }
        .hidden_button {
            width: 100%;
        }